Now as regards what the balloon shall take up, that must be for your own taste to decide. All the resources of pyrotechny are open to you, and by discreet use of Bickford’s fuse and quickmatch you may get innumerable combinations. One of the most brilliant pyrotechnic devices is the ignition of a tuft of magnesium fillet; but it is somewhat expensive, and, if carried out, will make a hole in your pocket-money. All the magnesium balloons I have seen had the magnesium tuft ignited before the balloon was let off; but were it desired that the magnesium should only commence burning when the balloon had got some way upon it, nothing would be more easy. All that is necessary to do would be to wet the magnesium tuft with resin dissolved in benzoline, and then, whilst still wet, dust it over with mealed gunpowder. On drying, this prepared tuft will burst into flame on the slightest provocation. If you do not know how to effect this by judicious employment of Bickford fuse and quickmatch, I shall have written to small purpose.

The following hint is well worthy attention by such of you young gentlemen as are not overburdened with pocket-money. Fine zinc shavings will burn, and emit a bright light something after the style of magnesium, and may be procured at any zinc-worker’s for a mere trifle. A moderately brilliant effect may be got out of a tuft of zinc shavings well dusted with resin and mealed powder whilst made wet with benzoline. If you don’t expect too much out of this zinc-burning expedient, perhaps you will not be disappointed; but at any rate I have not commended the alternative to you very warmly. Of course, a portion of magnesium may be mixed up with the zinc shaving tuft, to the latter’s advantage, just as it has been experimentally proved that flint soup is all the better for a portion of onion and carrot, and better still for a portion of meat, peppered and salted.

Before concluding let me just hint at a very effective possibility in the way of pyrotechnic device, equally applicable to both fire and gas balloons, but which I have never known carried into practice. You will see that it is a main object in balloon pyrotechny to make a balloon carry the greatest amount of pyrotechnic effects using the minimum of weight. Thus, supposing it were desired to cause a succession of explosions, each equalling in noise the discharge of a forty-pounder cannon, large maroons would give such a noise, but no toy balloon would be competent to lift the maroons. Now a mixture of two volumes hydrogen with one of oxygen yields an explosive mixture of tremendous violence. Even a small soap-bubble blown with this mixture and fired is deafening. I have no doubt that an ox bladder filled with this mixture and ignited would make a report equal to that of a forty-pounder gun. Several such bladders might be sent up with a very small toy balloon, and might be detached by means already described, so as to explode whilst falling. The exact modus operandi would be as follows:—Take a blue-light, and with a bradawl make a few transverse holes just above the sealing-wax closure; then smear the closed and transversely perforated end with a paste of mealed powder and water. After drying the neck of the bladder already charged with mixed oxygen and hydrogen, it is to be tightly bound down upon the blue-light, thus—

Bickford fuse and quickmatch would easily enable you to achieve the rest, supposing you to have given proper attention to preceding instructions.

CHAPTER LX.—MODEL BALLOONS AND ALL ABOUT THEM.
By a Professional Aëronaut and Balloon-maker.

lthough balloon ascents are now matters of everyday occurrence, and scarcely a fête takes place at any of the public gardens without the announcement of an ascent to be conducted by some well-known aëronaut, yet there are very few people who really know anything practical about balloons or their construction, so we often read graphic descriptions of perils surmounted and deeds of heroism performed by aërial travellers, which aëronauts know to be utter impossibilities—such, for instance, as the climbing to the top of a balloon by the network in order to open the valve at the top and allow the gas to escape; not to mention other marvellous fictions invented by the imaginations of ‘sensational’ newspaper reporters.

It is my desire in the present chapter to give the reader a thorough practical knowledge of that truly wonderful machine by means of which man is enabled to rise above his mother earth, and gaze upon her beauties from a height unattainable otherwise. And, as it is first of all necessary to dispel the ignorance which prevails upon the subject, I shall commence by showing what a balloon is not, then I shall proceed to describe what it is, and finally I hope to give such information as shall enable my readers themselves to construct a perfect model of a balloon, such as, if made on a proportionately increased scale, would be capable of carrying into the air one, ten, or twenty people.

That the science of aërial navigation has a strong fascination for adventurous dispositions is a proposition which none will gainsay; and the very danger attending a balloon ascent adds to its pleasurable excitement. This danger, however, is not only, nor even chiefly in the air, but in the descent to the earth, when the greatest caution has to be observed to alight upon a favourable spot: and sometimes consists in the reception accorded to the traveller on his arrival upon terra firma, as the following little adventure will show.

I have been from my childhood a lover of ballooning, having been, I might almost say, born to the business, which was taught me by my godfather, the veteran aëronaut, Charles Green, whose memory is yet held in reverence by many who knew and loved him while he lived. I had frequently been taken by him in his various ascents, and as I grew into man’s estate I was able to be useful to him in his trips. On one occasion an ascent had been announced from what were then known as the Surrey Zoological Gardens. Everything was duly prepared, the balloon was filled with gas, and at the appointed time Mr. Green and I sailed gently into the sky amid the crash of the band and the cheering of the people, which grew fainter and yet more faint, and at last quite inaudible, as we mounted higher and higher towards the azure vault above us.

It was a lovely afternoon in October, and a gentle breeze wafted us slowly away from the mighty city, over green fields wherein the grazing cattle looked rather smaller than ants, over villages whose toiling inhabitants seemed but tiny specks in the universe; until at length a light mist spread itself over the country.

My relative, experienced aëronaut though he was, manifested signs of anxiety as to the safety of our descent; for we had for some time past commenced descending by letting out the gas from the valve at the top of the balloon, but the nearer we approached the earth the denser became the fog, while the shades of evening warned us that the descent was an imperative necessity. Hoping to alight in the open country, we let fall the grapnel, which very speedily caught hold of something which checked our progress. Unluckily this something proved to be a tree, and not the earth, as we had, of course, hoped it would be.

‘Charlie,’ said Mr. Green, ‘there is only one thing to be done, and that is for you to get down and release the grapnel from the tree, and ascertain if you can how far we are from the open, for if the net gets entangled with the boughs we shall be lost, and the balloon spoiled.’

To me, well versed as I was in all kinds of gymnastics, it was a matter of little difficulty to descend the rope which connected us in some way with the earth; so putting another stout cord on my shoulder I went down ‘hand over hand’ until I found myself in a large elm-tree, and as the fog had risen considerably above the earth I was able to make out our whereabouts. We were in the middle of a thickly wooded park, though about two hundred yards to the east, in the direction in which we had drifted, I could see a large open space eminently fitted for the descent. I called out this information, cheerily adding that there was no fear of the net being broken this time. Then I quickly disengaged the grapnel, upon which the balloon sprang up gaily into the air, and next prepared to make my own descent from the tree by means of the cord with which I had provided myself. No sooner had my feet touched the ground than I felt myself roughly seized by two men, who bound my arms behind me in a jiffy, and at once commenced to rate me soundly.

‘Ah!’ said the elder man, savagely, ‘we’ve caught you at last, you rascal, have we? So you’re the chap as steals our governor’s pheasants, is it?’

‘Yes,’ grinned the other, ‘and it’s with a net as you takes ’em, just as I thought! We’ll see what the squire’ll say to you now!’

‘But, my good friends,’ I observed, ‘you have made a mistake. I’m not a poacher, but have just come down from a balloon, and shall be very much obliged to you if you will help me to secure it when it descends again, as it will, away from the trees.’

‘Ha! ha! ha! Ho! ho! ho!’ roared my captors, ‘that won’t do for us, young master. There ain’t no b’loon up that there tree; but what there is there is your pal with the net what you catches the pheasants with; and,’ raising his voice, ‘he may as well come down at once, ‘cos we means nabbing him now we knows where he is.’

Some passing labourers were hailed and stationed round the tree to await the descent of ‘the other poacher,’ while I, whose remonstrances were of no avail, was hurried up to ‘the house,’ wherein sat, on his chair of state, the redoubtable ‘squire,’ to whom the domain belonged, and whose pheasants I was accused of stealing. Again I told the story of the balloon. The old gentleman regarded me with stern dignity, and, wagging his finger at me, solemnly inquired of the keepers (my captors) whether they had seen any balloon. Upon receiving a reply in the negative, he assumed his most magisterial demeanour.

‘Young man,’ he said, ‘it is sad indeed to find a person of education in your unfortunate position. Your tale of having come down in a balloon is as audacious as it is ridiculous. No balloon was seen by my servants, and you were seen to descend a tree, your companion remaining no doubt until the hue and cry should be passed. I have lost many pheasants lately, and there can be no doubt now as to who the culprits have been. I have nothing more to do now than to commit you for to-night to the lock-up, and the case will be investigated in the morning.’

‘But, sir,’ I pleaded, ‘pray send to the field just outside your park, where my friend will doubtless be found by this time with his balloon, which could not be seen by your keepers on account of the fog, but which was then hovering above the tree in which the grapnel had caught, and from which I extricated it.’

Happily for me this request was acceded to, and in due course Mr. Green made his appearance and corroborated my statement, upon which every attention was lavished upon us both. We received an invitation to dinner, and, instead of passing the night in a village cell, I slept on the bed of down of our most jovial and courteous host, who would not hear of our leaving him until we had enjoyed a good night’s rest under his hospitable roof.

But I am in very great danger of forgetting that my present intention is to write a practical treatise, not to prattle about my adventures, so I will set myself seriously to work at once; and will begin by showing in a few words what a balloon is not.

In the first place, a balloon is most certainly not what it is sometimes erroneously called—a flying machine. One might as well compare the gracefulness of a good swimmer with the aimless floating of a dead dog, as to pretend that the helpless drifting of a balloon has anything in common with the as yet only partially accomplished science of aërial flight. What, then, is a balloon, and how is it constructed?

A balloon for carrying passengers consists of a certain number of gores cut in such a form that when they are sewn together they form a perfect sphere, the lower part or neck being elongated, which gives a pear-shaped appearance. This elongation at the neck is made in order to allow the gas to pass freely into the balloon during inflation. On the top is placed a valve, which is a circular double door composed of two semicircles. To each of these semicircular openings is attached a line, which, meeting a little lower down, form one line, which passes through the centre of the balloon, and comes out at the neck; so that when the aëronaut desires to descend he lets out the gas by pulling the line. The doors open inwards, and close themselves by means of springs with which they are fitted.

The balloon itself is composed of very fragile materials. It is merely a gas-holder, and is nowadays almost invariably made of fine cambric well varnished. Silk was the first-used material, but it is a needless expense. Thus it will be seen that the balloon itself has practically no strength in it whatever. All the space, however, and the pressure of the gas, are held in by a netting, which covers the whole of the balloon, to which it is fitted exactly, being shaped from the original pattern gore of the balloon itself—to be fully described hereafter.

Just below the neck of the balloon is a HOOP, to which all the netting lines are fastened. This hoop is made of ash, and is about three feet in diameter, all the strain of the balloon being concentrated at this point.

Below the hoop is attached the CAR, which is a large wicker basket suspended from the hoop by eight cords—technically termed car lines; and fastened to the hoop is a strong rope, generally made of flax, about 100 feet in length, which carries the anchor, or ‘grappling-iron,’ as it is called by aëronauts. This ‘grapnel’ differs in appearance from an ordinary anchor in that it has five prongs instead of only two. Inside the car are placed several canvas bags containing sifted sand, which is used as ballast, to regulate the ascending power of the balloon. The car also contains a few other requisites, notably a ‘liberating iron’ for letting the balloon go when all is reported ready, and an aneroid barometer, to show the altitude attained, &c.

Before entering upon the detailed description of how to make your model balloon, I think it will be well to give some idea of what an ordinary ascent really is, for it is of importance that we should realise what we are about before we proceed to construct the machine which is to carry us from the nether atmosphere into unknown regions miles above the earth, whether the ascent is to be made for scientific purposes or merely for amusement. I do not think there are many living men who can give better instruction on this point than myself, seeing that I have already made no less than eighty-four ascents, while I hope to make as many more before old age and infirmity put a stop to my ballooning career.

Balloons constructed to carry passengers vary very much in size, the smallest being of 18,000 cubic feet capacity, capable of raising two people only—the aëronaut and one passenger. This, or a little larger, is the size of the balloon now generally used, larger balloons being made principally for scientific purposes. Such a one was the celebrated ‘Mammoth,’ supplied by Mr. Coxwell for the memorable investigations by Mr. Glaisher about the year 1863, of which I suppose you may probably have heard, and concerning which it may interest you to learn that on two of their ascents I had the honour of accompanying those famous aëronauts, the ascents taking place on both occasions from the Crystal Palace, and the descents once at Singlewell, near Gravesend, and once near Woking.

The gas with which an ordinary balloon is filled is the gas supplied by the gas companies for street and house lighting, which is called carburetted hydrogen. Pure hydrogen is seldom employed for balloon inflation, though it may be interesting to state that the big captive balloon at the Paris Exhibition was initiated with pure hydrogen, manufactured with sulphuric acid, zinc, and water. This is called sulphuretted hydrogen, and possesses nearly double the lifting power of coal-gas. A balloon held down by a rope requires great ascending power, therefore all captive balloons should be inflated with pure hydrogen. The very great expense of this gas, however, prevents its use in ordinary cases.

The balloon being filled with gas, the aëronaut and his passenger take their seats in the car, ready to ascend. The first thing to be done is to untie the neck of the balloon, which has been fastened up with a piece of string or a handkerchief since the hose-pipe was removed, when the balloon was quite inflated. The object of having the neck of the balloon wide open is this: Directly the balloon rises expansion takes place, owing to the rarefied state of the atmosphere, and the higher it ascends the more rarefied the air becomes, and consequently the less atmospheric pressure is there upon the balloon, the natural result being that the gas expands, and makes its way by degrees out of the neck. If there were no such escape, the balloon would burst. When the neck is wide open, those in the car can see into the middle of the balloon, which has a very curious appearance.

We are now supposed to be ready for starting, there having been placed at the bottom of the car several more bags of ballast than are known to be required. These are handed out, one by one, until the weight in the car is about equal to or a little lighter than the ascending power of the balloon. Then the aëronaut, feeling himself master of the situation, calls out in a loud voice, ‘All hands off!’ At the word of command the assistants, who have been keeping the car down, leave go their hold, and the balloon rises slowly and majestically into the air. (Please now to put yourself into the place of the passenger making his first ascent, with eyes and ears open to take in all the instruction that can be conveyed to him.)

When about fifteen feet in the air the passenger, who has by this time probably worked himself into a somewhat feverish state of excitement, is astonished and considerably alarmed by a sudden jerk or shock, and the equally sudden arrest of the balloon in its upward journey. The fact is that we had not finally left our mother earth, but have been pulled down again by a rope, held by the assistants, which was attached to the hoop by an instrument called the ‘liberating iron.’ The aëronaut himself lets the balloon take its final departure when he touches a lever attached to the liberating iron, and we are being pulled down again on the present occasion because it is found that we have too much ascending power, and can take in another half bag ballast; and the more ballast a balloon can carry the better, as sometimes ballast is found to be worth its weight in gold—or rather, worth as much more as life is worth more than the most precious of all earthly possessions. At the risk of fatiguing you by a digression, I will explain how this is.

The use of ballast is in getting rid of it. When the aëronaut desires to descend he pulls the line I have before described, letting the gas out of the valve at the top, when the balloon immediately comes down. Perhaps unfavourable weather, with a strong wind, may have arisen, and he suddenly sees beneath him a village, or a barn, or perhaps he has been borne out to sea. In any of these cases almost certain death would be the result of a sudden descent. So he throws some ballast out of the car, which immediately lightens it, and the balloon rises up again and carries him over the danger to some place where the descent may be made in safety. If all the ballast be injudiciously or prematurely expended, there is danger indeed in descending; and I know of one instance, at least, in which a daring but unskilful aëronaut was killed, who, in all human probability, would have been now living if he had had with him but one more bag of ballast. So, you see, I do not exaggerate when I say that ballast is sometimes worth much more than its weight in gold.

To return to our ascent. Having taken on board the extra ballast, ‘All hands off!’ is again called out aloud; again we ascend into the air, the band strikes up, the guns are fired, the aëronaut, his hand upon the liberating iron, salutes the public, the rope is detached, and we are off!

And now I will leave my passenger gazing over the side of the car, lost in amazement at the grandeur of the scene beneath him, as the horizon, rising with our ascent, discloses to view an expanse of country of which he could have had no previous conception; for I have work to do. First, I look at the aneroid barometer and find that we have arrived at an altitude of about three thousand feet, which is the height usually attained in an ordinary ascent. The gas has been coming out of the neck very freely, and the balloon is consequently beginning to descend. As we do not intend to land just yet, however, it is necessary to check the descent by parting with a little ballast, which is thrown out over the edge of the car, and has the appearance of smoke as it passes into space.

Now we are about the same weight as the atmosphere with which we are travelling. Although there was only a slight breeze on the surface of the earth, the upper current is considerably stronger, and we are going along with the clouds at a speed of a little less than a mile a minute. Yet, though travelling at this rate, we appear to be in a dead calm, and if a feather be dropped from the car it will sink slowly in a perpendicular line underneath us. When a balloon has left the earth there is no perceptible motion in it whatever. We seem to be stationary, while the fields have the appearance of rushing quickly along beneath us. We are really, as it were, part and parcel of the air, and as the current moves so we drift with it, like a cork on a running stream; and if it were possible to put you blindfold into the car of a balloon, you might be taken up into the clouds and brought down again without your being any the wiser—indeed, without your knowing anything at all about the journey.

This I have been telling you while we have been sailing along through the beautiful summer sky, taking in deep gulps of the pure air, and looking down and around upon the glorious moving panorama. But now I must leave you again to your own resources, for it is time that we should prepare for the descent, and I require to have all my wits about me. The grapnel, which is hooked on to the edge of the car, is lowered down by the rope, which is 100 feet in length, and firmly fastened to the hoop. Now we must exercise judgment and caution in selecting a proper place on which to make our descent by looking along the earth in the direction in which we are travelling. We must not come down among the crops, or we shall have the farmer after us for damages. The trees are particularly dangerous, as we have seen. So are the telegraph wires, for even if they should not destroy us, it would go hard with us in the Law Courts if we were to damage them. An aëronaut must thus have his eyes wide open, and be able to see some miles in front of him; and he must try to make for some open park or pasture land, which he can distinguish from land on which crops are growing by the cattle grazing. So the valve is opened a little, with the immediate effect of causing the balloon to descend to from 1000 to 500 feet above the earth.

Now we pass rapidly over the country until we arrive over the selected spot, when, giving the valve another stout pull, the balloon obeys and drops. Perhaps, on a closer inspection, the place we have chosen is not so favourable as it appeared at a distance; then, of course, we have to part with a bag of ballast, and ascend again until we reach a more suitable alighting ground. The grapnel takes hold at last, and on a calm day the balloon may be brought down as lightly as a feather by the regulating of the ballast; but when there is a strong current of air the grapnel will sometimes trail, which causes the balloon to jerk unpleasantly, but with good management there is no danger.

Having thus taken you up, and brought you safely down again, I will redeem the promise I make in the title by showing you

How to make a Model Balloon,

which, simple as it may seem, is in reality a very intricate operation, and you will find, as you follow me, that there is a great deal to be learned. I do not fancy you will think it at all dull work, however; on the contrary, while it is instructive and scientific, it will afford you many hours’ agreeable and innocent amusement. You have been taught how to make yachts, and have been very delighted, I have no doubt, when your first attempt at shipbuilding has proved successful, and you have seen your ship float upon the water and carry sail; but I do not think there are many readers who have had the opportunity of learning how to make a balloon which will actually hold gas and ascend into the air. Perhaps you will find this latter part of my treatise rather technical, yet I hope you will give it your attention, for I am about to endeavour to let you know more about this subject than has ever been written upon it before; and though I do not expect, or wish, to make you all professional aëronauts, I do certainly desire to awaken in your minds an interest in ballooning—a science which is daily becoming of more recognised importance.

In making a balloon the first thing to be done is to take into consideration how many gores, or strips, will be required to form a balloon of any given diameter. For instance, if a balloon be required of the circumference of 3 feet, there will be twelve gores each 18 inches in length (that being half the circumference), and 3 inches in width at the equator, but tapering at each extremity, as will be hereafter described. Now divide the paper of the pattern gore into four equal parts, and then describe a circle in the centre (Fig. 1).

Divide one quadrant of the circle into any given number of parts—say seventeen. Then drop perpendiculars parallel with line C from each point of the divisions, intersecting line B in the quadrant. Now divide line B from centre of circle to end of pattern in seventeen equal parts, and raise perpendiculars from each point of division, as in Fig. 2.

Next draw horizontal lines, or measure off with compasses from each point of division in the quadrant, cutting or intersecting the seventeen corresponding lines as shown, and with a free hand, or by the aid of a French curve, connect all these points together, as shown in Fig. 3.

Having now got a quarter of the pattern, it must be cut round, as shown, and transferred to the three other quarters, marked respectively in the figure A, B, C, which will be the pattern for a sphere. This is technically known as striking out a pattern gore by an intersection of lines, and this is quite near enough for the paper balloons, on which you must practise until you are sufficiently advanced in the science to enable you to begin on the proper material. There is another method which is still more accurate, in fact, will ensure absolute mathematical correctness, and that is by a calculation of a series of decimals corresponding with each of the seventeen perpendicular lines shown beneath (Fig. 4).

Suppose, for example, that the diameter of the balloon to be constructed is 20 ft., and that it is required to make it of 12 pieces; then, in order to draw the pattern for those pieces, find the circumference of the balloon, which is 62·83 ft., and, dividing it by 4, the quotient is 15·7 ft. Make, therefore, A D equal to 15·7 ft., and D E likewise of the same length. Divide the circumference, 62·83 ft., by 24, which is double the number of pieces that are to form the balloon, and the quotient, 2·618 ft., is the length of D C, and likewise of B D, so that B C is equal to 5·236 ft. Then, having divided the line A D into 18 equal parts, and having drawn the parallel lines from those points of division, find the length of each of those lines by multiplying 2·618 by the decimals annexed to that line. Thus 2·618, multiplied by 0·99619, gives 2·608 ft. for the length of f g, and, again multiplying 2·618 by 0·98481, the result gives 2·578 ft. for the length of h i, and so of the rest. In cutting the pieces after such a pattern, care should be taken to leave them about three-quarters of an inch all round wider than the pattern, which will be taken up by the seams; and the same rule must be borne in mind whether you are experimenting upon paper patterns, or upon the materials required for a large balloon. Fig. 4 will illustrate the foregoing instruction, and those who like to take the trouble to prove the sum will take all the more interest in the manufacture of their balloon.

These decimals have been calculated by a mathematician, and are available for any sized balloon.

Now we come to the neck, the pattern of which may be drawn with a free hand, and maybe left to your own fancy, with this proviso—that the length ought not to exceed more than one-fifth of the whole length of the pattern. In Fig. 5 you will see what the neck should be, the dotted line showing the spherical portion of the pattern gore.

Small gas-balloons are generally made of tissue-paper, varnished over with boiled oil, which gives them a very transparent and skin-like effect. Sometimes gold-beater’s skin is used, but it is very expensive, and paper answers the same purpose. Supposing that you are about to begin upon a paper balloon, the first thing to be done, before making your pattern gore, is of course to select your paper. Ordinary tissue is manufactured from the size of 20 × 30 inches square. There are other sizes made of a stronger quality, suitable for larger balloons than that of three feet circumference, upon which I recommend you to practise, as this is a handy size, while the above-sized paper—obtainable everywhere—cuts in well for the width to make the pattern gore, though, for length, you will have, probably, to paste two sheets together.

When you have a sufficient number of lengths ready for cutting out, place them, one on the top of another, on a flat board; then place the pattern gore on the top, and, with a sharp knife or razor, cut the whole out at once, taking care not to cut the pattern gore. You will do well also to place a few weights on the top to keep the whole lot in place. After you have cut one edge, move your pattern about a quarter of an inch away from the edge that is cut. This is to allow for the ‘lap,’ as it is called, whether in pasting a small balloon or sewing a large one, for bringing the gores together in case you have not made such allowance on the pattern. In pasting together—in the case of paper balloons, or sewing in the case of larger balloons—you should take care, for the sake of effect, to do so in alternate colours. Red and white, yellow and white, green and black, all make effective contrasts, but these minor details may be safely left to your own taste. Paste them, first in pairs, then in fours, &c., in the following manner. Having provided yourself with a large, smooth pasteboard, begin by laying upon it a white gore, and then place carefully over it a coloured one, showing the ‘lap’ on the one underneath to allow for the folding. You can do this by carefully manipulating the gores with the fingers, or, still better, by the means of a palette or any other flat knife. Then, with a ‘dabber,’ as it is technically termed—a clean duster will answer the purpose—press down the overlapping seam the whole length, and immediately hang it up to dry, and proceed to do the same thing with the others, never attempting to paste others together until the first are perfectly secure by drying. A little alum should be put into the paste you are using for the purpose.

When you have pasted all the gores together, and they are quite dry, blow the balloon out with a pair of bellows through the neck. You will find at the top, where all the points of the gores meet, a small hole, which will let out the air with which you have filled your balloon, and à fortiori the gas with which it will have to be filled presently, the gas being lighter than the air, and so more anxious to make its escape from its imprisonment. At all events this is very probable, even in the most carefully and scientifically constructed balloons. To obviate this fatal mistake, therefore, you must cut a round piece of paper, which is called the cap, answering to the valve in a real balloon, and carefully paste it over the meeting-places of the various gores. For you must bear in mind that a balloon is not a balloon at all unless it be perfectly air-tight.

Now let out the air by gentle pressure, and fold up the balloon, gore over gore, and commence the varnishing, which is laid on as thinly as possible with a small piece of flannel. The varnish used is simply boiled oil, which can be obtained from any oil and colour shop. After you have carefully varnished the whole of the gores, blow the balloon out again, and hang it up by the neck until it is dry, a process which will take about twelve hours.

The material used in the construction of balloons for carrying passengers is Scotch cambric—not silk, as is erroneously supposed. Silk has not been largely used in the manufacture of balloons for the last forty years, and I need hardly say that it is not pasted, as in a paper balloon, but sewn with double rows of stitches, and varnished exactly in the same manner as I have already described.

In big balloons, the most important part of all is

THE NETTING.

And I shall now describe the way in which, if you desire to make your model perfect, you must set about this portion of your manufacture, which, however, you can dispense with if you please in a paper gas-balloon. As I told you before, there is scarcely any strain whatever on the balloon; in fact you could make a large paper balloon to contain 20,000 cubic feet of gas, and if it were covered with a properly fitting net it would, for one ascent, answer the same purpose as a cambric balloon, the reason for making it of a material at once light and strong being to enable it to stand the wear and tear of laying out, folding, packing, &c. The first thing to be observed in making the net of a balloon is to take the same pattern gore as the balloon itself was cut from. Now draw a longitudinal line through the centre A (Fig. 6), the gore being reduced to two halves. Divide one half by the same rule as that on which you originally cut the pattern gore, the object of this division being to get the meshes of the intended netting reduced to such a small scale that four meshes may cover each gore. Measure on the centre line A, the distance B C, and half as long again. Draw a line parallel to B C from D to E.

Now draw a diagonal line from D to C, which will give you an angle of about sixty degrees. Now cut a templet or set square out of card or thin wood, corresponding with angle C B D, thus (Fig. 7).

Now with line F G on the templet corresponding with line D E in Fig. 6, draw E F, and continue this until you come to the crown—i.e. the part where the valve is fixed. Now draw diagonal lines, similar to B E, all the way up (as shown in Fig. 6), which gives the different sizes of the meshes to be used in forming the net from the equator to the pole; and supposing you have decided to have twelve gores to form your balloon, you would then have forty-eight rows of meshes to go round the balloon, and so on, according to the number of gores of which the balloon is composed.

Now for making the netting from the equator to the hoop, concerning which the following instructions are to be observed. The first set, or row, of meshes below the equator are to be of the same length as those at the equator with one-fourth added—i.e. one-quarter longer; the second set, or row, of meshes from the equator are to be one-quarter longer than the last; the third set from the equator to be one-third longer than the second set; the fourth set one-third longer than the third set; the fifth set, or row, is called the drawing line, and is one-third longer than the last. Then come the cords, or leading lines, which are fastened to the hoop, to which the car is attached. This is the true way to make a proper balloon net, and on the same principles you may make the meshes much larger by setting them out three to the gore instead of four—indeed, they are often made in this manner for economy’s sake—and, instead of having a leading line to each row of meshes, two are frequently blended into one. The material to be used should be the best three-strand Italian hemp netting-line, and you must bear in mind that the meshes at the crown should be very fine, increasing in strength as you go downwards.

The last process in connection with this subject is

THE GAS

with which the balloon is to be inflated. It may be well for you to refer to the chapter by Dr. Scoffern, on the apparatus and method of inflating balloons with hydrogen gas, with his illustration of the apparatus; but as I am going more minutely into details, I give you here the quantities of ingredients for generating sufficient gas to fill a given-sized balloon. Thus, for instance—

The zinc and water are put into the generator first and corked down, and connections made with the iron or composite pipe to the purifier, which merely contains water (three parts full), and a small quantity of lime—say, a piece the size of a walnut to a pint of water. Should there be any leakage round the pipe, stop it with loam or clay. Pour the acid into the generator, through the feed-pipe, with a funnel, in small quantities at a time. As the gas passes into the balloon you can tell how quickly it is forming by the bubbling sound which is taking place in the purifier. If you were to pour all the acid into the generator at once, you would burst it. When you hear the bubbling noise diminishing, add more acid.

Now there is another point you must understand—i.e. to be able to find the cubic capacity in feet of a balloon of a given diameter, which is done in the following simple manner:—

Diameter 2 ft. (or 24 in.). Multiply by diameter = 4. Multiply by diameter again, = 8. Now multiply by decimal numbers ·5236 = 4·1888.

The same decimal number will apply to any given diameter, and you see by this rule that a balloon of two feet diameter will contain four cubic feet of gas, and that the quantities of ingredients, &c., required are as given above. I hope you will excuse me for taking you to school again, but I am anxious to make this chapter as complete as possible.

COST.

With reference to the cost of the materials to be used in the construction of balloons, it is obviously impossible to enter into details without knowing the size of the balloon to be constructed. The following general instructions, however, may be found useful.

Strong tissue-paper, which measures twenty by thirty inches, costs about sixpence per quire, one quire being amply sufficient for a three-foot balloon.

Scotch cambric, which is forty-four inches wide, costs one shilling and twopence per yard, and you will be able to calculate how many yards are requisite for your purpose.

Boiled oil costs about fourpence per pint, half a pint being sufficient to varnish a three-foot paper balloon.

Tissue-paper can be had of all colours.

With regard to the netting, which is technically known and must be asked for as ‘netting line,’ it varies in size, and costs about two shillings per lb.

With these few remarks I leave you to the construction of your balloon, which I hope you will find an agreeable and not too difficult task.

CHAPTER LXI.—SMUDGEOGRAPHY; OR, HOW TO TELL THE CHARACTER BY HANDWRITING.

This is a portrait of Billy Baker (Fig. 1). It is not by the famous Flemish artist Van Daub, whose works are to be found in every gallery in Europe, but by his distant relative Von Smudge, whose efforts need only to be known to be equally appreciated. It is understood to be a successful attempt to tell Billy’s character ‘from his handwriting.’ It is not a flattering likeness. We are afraid Von Smudge found that the hand was not in due submission to the will. It, however, shows Billy as having a deal of breadth and very substantial understanding.